How and Where Do I connect these pins from a pH Meter?

SumukhPrasad · October 2, 2019, 10:31am

Hello there, Can anyone tell me where and how to plug this in, and what code to use?

https://drive.google.com/uc?id=1s2Chegq_PChMdfLBMyiq-emqhh4v1zWu(image larger than 4 MB)

(Sorry if the photo takes time to load.)Thanks in advance.

system · October 2, 2019, 11:26am

I'm going to take a wild guess that the output pins marked O/P bottom centre, are an analog value across their + and - pins.

That would indicate - to Arduino ground and + to an analog input Ax pin, and just read it with analogRead(), but before you do that check the output voltage with a voltmeter that it's not over 5V ever.

Looks like the board has its power supplied bottom right, but does it say 9V?

edit... looks like this one? Says there, it's analog with output is 0.5-3V.

SumukhPrasad · October 2, 2019, 11:41am

I'll try the idea.Thanks

system · October 2, 2019, 11:49am

SumukhPrasad:
I'll try the idea.Thanks

But finding the datasheet would be a better option.

SumukhPrasad · October 2, 2019, 12:08pm

I have the data sheet, but it doesn't say anything about what goes to what.

SumukhPrasad · October 2, 2019, 12:43pm

Nope. That doesn't work. I get a constant zero.

system · October 2, 2019, 12:49pm

Well it seems from the link I posted in #1, which admittedly is perhaps not your actual model, but looks very very similar, that just wiring the output to an analog input should work. It says:

Perhaps post your code and a link to the datasheet you have.

system · October 2, 2019, 12:56pm

What voltage do you read with your multimeter on those outputs?

(Presumably you have the probe connected to the bnc?)

SumukhPrasad · October 2, 2019, 1:04pm

First, which ports? A0-A15 or AREF? Second, I don't have a multimeter, but the data sheet says says that the max. output is 5 volts.

Here is the code.:

int phval = 0;
#include <Arduino.h>
#include <TM1637Display.h>

// Module connection pins (Digital Pins)
#define CLK0 41
#define DIO0 43
#define CLK1 23
#define DIO1 25

#define TEST_DELAY 2000

const uint8_t SEG_pH[] = {
SEG_A | SEG_F | SEG_E | SEG_G | SEG_B,
SEG_F | SEG_E | SEG_G | SEG_B | SEG_C,
SEG_G | SEG_D,
};

TM1637Display display0(CLK0, DIO0);
TM1637Display display1(CLK1, DIO1);

void setup()
{
Serial.begin(9600);
pinMode(27, OUTPUT);
pinMode(29, OUTPUT);
digitalWrite(27, HIGH);
digitalWrite(29, LOW);
pinMode(45, OUTPUT);
pinMode(47, OUTPUT);
digitalWrite(45, HIGH);
digitalWrite(47, LOW);
pinMode(A1, INPUT);
int k;
uint8_t data[] = { 0xff, 0xff, 0xff, 0xff };
uint8_t blank[] = { 0x00, 0x00, 0x00, 0x00 };
display0.setBrightness(0x0f);
display1.setBrightness(0x0f);

// All segments on
display0.setSegments(data);
display1.setSegments(data);
delay(TEST_DELAY);
}

void loop()
{
phval = digitalRead(A1);
int k;
uint8_t data[] = { 0xFF, 0xFF, 0xFF, 0xFF };
uint8_t blank[] = { 0x00, 0x00, 0x00, 0x00 };
display0.setBrightness(0x0f);
/*Set PH VALUE HERE!!!!!!!!Get the first, second, third,
fourth digit of the ph value and calibrate to show the
value on the screen. */
data[0] = display0.encodeDigit(1);
data[1] = display0.encodeDigit(2);
data[2] = display0.encodeDigit(3);
data[3] = display0.encodeDigit(4);
display0.setSegments(data);

display1.setSegments(SEG_pH);
Serial.println(phval);

}

system · October 2, 2019, 1:37pm

Make this an analogRead()

 phval = digitalRead(A1);

I don't have a multimeter

Bzzzzt.... wrong answer

SumukhPrasad · October 2, 2019, 1:56pm

Thanks. Now I get a continuous stream of completely unrelated numbers when connected.

system · October 2, 2019, 2:05pm

SumukhPrasad:
Thanks. Now I get a continuous stream of completely unrelated numbers when connected.

You mean from here?

Serial.println(phval);

Those numbers are from 0 to 1023 for 0 to 5V, so x5/1023 to get voltage.

Then the datasheet of the sensor will tell you the relationship between volts and pH.

system · October 2, 2019, 2:13pm

By the way the voltage needs to be a float, and make the 5 and 1023 floats as well to make sure the maths happens correctly, as shown here:

float voltage= sensorValue * (5.0 / 1023.0);

SumukhPrasad · October 2, 2019, 2:21pm

Now I get a constant reading of 8 ph.
int phval = 0;
#include <Arduino.h>
#include <TM1637Display.h>

// Module connection pins (Digital Pins)
#define CLK0 41
#define DIO0 43
#define CLK1 23
#define DIO1 25

// The amount of time (in milliseconds) between tests
#define TEST_DELAY 2000

const uint8_t SEG_pH[] = {
SEG_A | SEG_F | SEG_E | SEG_G | SEG_B,
SEG_F | SEG_E | SEG_G | SEG_B | SEG_C,
SEG_G | SEG_D,
};
char myChar[10];

TM1637Display display0(CLK0, DIO0);
TM1637Display display1(CLK1, DIO1);

void setup()
{
Serial.begin(9600);
pinMode(27, OUTPUT);
pinMode(29, OUTPUT);
digitalWrite(27, HIGH);
digitalWrite(29, LOW);
pinMode(45, OUTPUT);
pinMode(47, OUTPUT);
digitalWrite(45, HIGH);
digitalWrite(47, LOW);
pinMode(A1, INPUT);
int k;
uint8_t data[] = { 0xff, 0xff, 0xff, 0xff };
uint8_t blank[] = { 0x00, 0x00, 0x00, 0x00 };
display0.setBrightness(0x0f);
display1.setBrightness(0x0f);

// All segments on
display0.setSegments(data);
display1.setSegments(data);
delay(TEST_DELAY);
}

void loop()
{
phval = (((analogRead(A1)*5)/1023)/0.375);
int k;
uint8_t data[] = { 0xFF, 0xFF, 0xFF, 0xFF };
uint8_t blank[] = { 0x00, 0x00, 0x00, 0x00 };
display0.setBrightness(0x0f);
/*Set PH VALUE HERE!!!!!!!!Get the first, second, third,
fourth digit of the ph value and calibrate to show the
value on the screen. */
Serial.println(itoa(phval, myChar, 10));
data[0] = display0.encodeDigit((myChar[3]));
data[1] = display0.encodeDigit((myChar[2]));
data[2] = display0.encodeDigit((myChar[1]));
data[3] = display0.encodeDigit((myChar[0]));
display0.setSegments(data);

display1.setSegments(SEG_pH);
Serial.println(phval);

Serial.println(itoa(phval, myChar, 10));
Serial.println(myChar[0]);
Serial.println(myChar[1]);
Serial.println(myChar[2]);
Serial.println(myChar[3]);
Serial.println(myChar[4]);

}

system · October 2, 2019, 2:28pm

Now I get a constant reading of 8 ph.

Maybe the pH is 8?

You need to make phval a float, as I said, and put .0 on the 5.0 and 1023.0

system · October 2, 2019, 2:43pm

But as far as I can see from a search, there is no Arduino float equivalent of itoa so not sure how you're going to get the digits out like you are for the integer.

In your other thread you just gave a value with no decimals:

SumukhPrasad:
if x is considered to be 375635

SumukhPrasad · October 2, 2019, 2:47pm

No. I tried different solutions. All seem to be 8. I know that soap has a different ph level than water.

system · October 2, 2019, 4:20pm

SumukhPrasad:
No. I tried different solutions. All seem to be 8. I know that soap has a different ph level than water.

Try vinegar vs baking soda....

Maybe there's some calibration routine that needs to run.

Did you make the pH reading a float to get some decimals?

system · October 3, 2019, 6:15am

But get a voltmeter. Then you can measure the output directly at the sensor's connections, and know if any "unacceptable" readings are dodgy right from there, or if it's the Arduino coding.

You don't want to be the wheel-tapper who condemns a whole train just because the hammer's cracked.

SumukhPrasad · October 3, 2019, 6:57am

Ive tried an Arduino "Voltmeter" project, which is supposed to tell me what voltage is present, if under 5 volts.
I did make them "float". I've tried:
-Salt solutions
-Soap
-Water
-Copper sulphate solution
-Sodium Hydroxide
-Baking soda.
All of them seem to be pH 9.

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How and Where Do I connect these pins from a pH Meter?

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